This free online interest calculator compares simple interest and compound interest side by side so you can see how your money grows under each method. Enter the principal, annual rate, time period, and compounding frequency to get instant results.
How to Use the Interest Calculator
Enter the "Principal Amount (₹)" you're investing or borrowing.
Enter the "Annual Rate (%)" of interest.
Enter the "Time (years)" for which the money is invested or borrowed.
Select a "Compounding Frequency" (Annually, Semi-Annually, Quarterly, or Monthly).
Click "Calculate Interest" to compare simple and compound interest results side by side.
Frequently Asked Questions
Simple interest is calculated as SI = (P × R × T) / 100, applied only to the original principal. Compound interest uses Amount = P × (1 + r/n)^(n × t), where the interest earned in each period is added back to the principal before the next period's interest is calculated, so it grows faster over time.
The compounding frequency (n) determines how many times per year interest is calculated and added to the principal. Choosing Monthly (n=12) compounds interest more often than Annually (n=1), which results in a slightly higher total amount for the same rate and time period.
The principal and time must be greater than zero, and the annual rate must be zero or positive. If these conditions aren't satisfied, the calculator shows "Invalid input!" instead of calculating a result.
Yes, this calculator is completely free and doesn't require any sign-up.